AU2012101965A4

AU2012101965A4 - Improvements in smart distribution transformer systems

Info

Publication number: AU2012101965A4
Application number: AU2012101965A
Authority: AU
Inventors: Jaun Park
Original assignee: UNISON NETWORKS Ltd
Current assignee: UNISON NETWORKS Ltd
Priority date: 2011-11-02
Filing date: 2012-11-02
Publication date: 2016-10-06
Anticipated expiration: 2020-11-02
Also published as: AU2012244333A1; NZ596170A

Abstract

A smart distribution transformer system comprising a fault monitoring system for monitoring the operation of one or more low voltage circuits being provided power 5 by the smart distribution transformer system, the fault monitoring system comprising a fault monitoring module adapted to: monitor the voltage and/or current associated with a low voltage circuit, determine the occurrence of a fault condition and develop an output signal upon receiving an indication from the determination module that a fault condition has occurred. 0 m =3 toff9

Description

IMPROVEMENTS IN SMART DISTRIBUTION TRANSFORMER SYSTEMS FIELD OF THE INVENTION

The present invention relates to improvements in smart distribution transformer systems. In particular, the present invention relates to fault monitoring in smart distribution transformers, the use of multistage capacitor bank circuits in smart distribution transformer systems and distributed control of smart distribution transformers.

BACKGROUND

In general, distribution transformers are used to transform the medium voltage on national distribution lines, such as for example 11 kV or 22 kV, into a lower voltage, such as for example 400 V or 415 V phase to phase. This lower voltage is then made available to customers of the power grid.

Currently available distribution transformers have conventional monitoring technology which predominantly includes maximum demand indicators. These indicators only capture the maximum demand that has been passed through the transformer.

Further, it is known to provide remote protection of three-phase distribution transformers through the remote monitoring of time related current and voltage levels. Also, systems have been provided to protect distribution transformers from overload, over temperature and low oil levels.

However, none of these prior known systems incorporate a mechanism whereby the operation of low voltage circuits can be monitored in order to determine whether a fault condition has occurred. Therefore, upon the occurrence of a fault with the low voltage circuit, the outage time for the customer may extend to an unacceptable level.

Historically, power flow through distribution transformers has been one way only i.e. from the network to the customer, but popularization of renewable generation (solar and wind) has enabled the general public to generate power back into the network. As existing transformers were not built for this purpose, they cannot efficiently condition the power flow back into the network. For example, the feeding back of the generated voltage may produce a voltage imbalance. Therefore, prior known distribution transformer systems do not as yet provide the ability to feed power back to a power grid in an efficient manner.

One important feature of a smart distribution transformer system is that the system must be able to reduce loads during either congested peak periods or during fault events. At present, this ability is managed manually via control centres. These control centres utilise ripple control relays in order to switch hot water cylinders on and off to adjust the load on the system. However, this high-level control is not always sophisticated enough to efficiently manage load during peak periods.

An object of the present invention is to provide an improved distribution transformer. A further object of the present invention is to provide an improved fault monitoring system for distribution transformers. A further object of the present invention is to provide an improved system for feeding power back to a power grid using distribution transformers. A further object of the present invention is to enable remote load control system for distribution transformers.

Each object is to be read disjunctively with the object of at least providing the public with a useful choice.

The present invention aims to overcome, or at least alleviate, some or all of the afore-mentioned problems.

Further objects and advantages of the invention will be brought out in the following portions of the specification, wherein the detailed description is for the purpose of fully disclosing the preferred embodiment of the invention without placing limitations thereon.

The background discussion (including any potential prior art) is not to be taken as an admission of the common general knowledge in the art in any country. Any references discussed state the assertions of the author of those references and not the assertions of the applicant of this application. As such, the applicant reserves the right to challenge the accuracy and relevance of the references discussed.

SUMMARY OF THE INVENTION

It is acknowledged that the terms "comprise", "comprises" and "comprising" may, under varying jurisdictions, be attributed with either an exclusive or an inclusive meaning. For the purpose of this specification, and unless otherwise noted, these terms are intended to have an inclusive meaning - i.e. they will be taken to mean an inclusion of the listed components that the use directly references, but optionally also the inclusion of other non-specified components or elements. It will be understood that this intended meaning also similarly applies to the terms mentioned when used to define steps in a method or process.

According to one aspect, the present invention provides a smart distribution transformer system comprising a fault monitoring system for monitoring the operation of one or more low voltage circuits being provided power by the smart distribution transformer system, the fault monitoring system comprising a fault monitoring module adapted to: monitor the voltage and/or current associated with a low voltage circuit, determine the occurrence of a fault condition and develop an output signal upon receiving an indication from the determination module that a fault condition has occurred.

According to a further aspect, the present invention provides a smart distribution transformer system adapted to transform power received from a power grid into a three-phase power supply for a plurality of consumers, wherein the smart distribution transformer system is further adapted to feed power generated by an inductive power generator back to the power grid, the smart distribution transformer system comprising a power factor monitoring system for monitoring the power factor associated with three-phase power supply and a multistage capacitor bank circuit adapted to be applied to the three-phase power supply, wherein the monitoring system is further adapted to control the application of the multistage capacitor bank circuit dependent upon the monitored power factor.

According to yet a further aspect, the present invention provides a smart distribution transformer comprising a control system for controlling the load applied to the smart distribution transformer, the control system comprising: a monitoring module adapted to monitor the operation of the smart distribution transformer and develop an output based on the monitored operation; and a control module adapted to wirelessly communicate with at least one smart meter where the smart meter is arranged to wirelessly communicate with at least one controllable device; wherein the control module is further adapted to transmit a control signal to the smart meter to instruct the smart meter to connect or disconnect the controllable device based on the output of the monitoring module.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 shows a block diagram for a smart transformer control circuit according to an embodiment of the present invention;

Figure 2 shows a block diagram for a smart transformer control circuit according to a further embodiment of the present invention;

Figure 3 shows a conceptual diagram of the smart transformer system operating smart meters according to an embodiment of the present invention,

Figure 4 shows a circuit diagram of a smart transformer system according to an embodiment of the present invention; and

Figures 5A to 5C show a smart transformer configuration according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

It will be understood that the system herein described includes one or more elements that are arranged to perform various functions and methods. The following portion of the description is aimed at providing the reader with an example of a conceptual view of how various modules and/or engines that make up the elements of the system may be interconnected to enable the functions to be implemented. The conceptual diagrams are provided to indicate to the reader how the various data elements are processed at different stages by the various different modules and/or engines.

It will be understood that the arrangement and construction of the modules or engines may be adapted accordingly depending on system and user requirements so that various functions may be performed by different modules or engines to those described herein, and that certain modules or engines may be combined into single modules or engines.

It will be understood that the modules and/or engines described may be implemented and provided with instructions using any suitable form of technology. For example, the modules or engines may be implemented or created using any suitable software code written in any suitable language, where the code is then compiled to produce an executable program that may be run on any suitable computing system. Alternatively, or in conjunction with the executable program, the modules or engines may be implemented using any suitable mixture of hardware, firmware and software. For example, portions of the modules may be implemented using an application specific integrated circuit (ASIC), a system-on-a-chip (SoC), programmable logic controllers (PLCs), field programmable gate arrays (FPGA) or any other suitable adaptable or programmable processing device.

Figure 1 shows a block circuit diagram for a smart transformer control circuit that forms part of the smart transformer according to this first embodiment.

The smart transformer includes a voltage transformer 101 with a primary winding for receiving the 11 kV source voltage and a secondary winding for outputting the 400/240 V output. It will be understood that the voltage levels on the primary winding and secondary winding may be different for different regions, countries or systems.

The voltage transformer is in electrical communication with an automated 11 kV switch with RTU (remote terminal unit) and logging capabilities. That is, the safe link device consists of electrical disconnects, fuses and/or circuit breakers and is used to isolate electrical equipment.

The system can be controlled via the SCADA (supervisory control and data acquisition) system.

It will be understood that this device may be any make or model, automated or not. A communications module 105 utilises a mesh radio system in order for the smart transformer to communicate with various components.

It will be understood that as an alternative, the smart transformer may be adapted to meet the requirements of the customer, or indeed any other suitable communication method may be used.

The mesh radio system is deployed across the power network to provide automation and control. The mesh radio system converts all radios into repeaters so that all radios can help send the message to the destination even if the destination is not visible to the source.

The smart transformer also has a transformer monitor 107 and LV (Low Voltage) bus logger 109. The term Low Voltage is understood to mean the voltage provided on the secondary side of the transformer, i.e. 400/415 V phase to phase or the 220/240 V single phase. It will be understood that the invention is not limited to this specific voltage value and that other suitable LV values may be used.

It will be understood that different logging devices may be used. For example, customer requirements may determine which type of logging device is to be implemented within the smart transformer.

This device is capable of measuring all power variables on the LV bus and serves as the master to a number of LV circuit loggers 111 (sub modules). The master device used according to this embodiment is a PLC which can analyse the data from each of the LV circuit loggers 111. This function provides fault indications and fuse blown indications.

Therefore, the smart transformer system uses two different types of logging device, a first type to monitor the 400 V bus bars and a second type to monitor each of the LV circuits provided to customers. Each of the LV circuit loggers 111 communicates with the master device over a communications channel. According to this embodiment, the communication is by way of a Modbus over an RS485 communications protocol. The master device collates the information from all the LV circuit logging devices and is polled by the radio over TCP/IP. According to this embodiment, the SCADA system polls the master device and subsequently the control room controller polls the SCADA system for the collected data. In this manner, if any of the collected data indicates that an alarm state has occurred, an alarm is triggered in the control room. It will be understood that other communication methods and/or protocols may be implemented as an alternative.

The master device PLC is configured to run a process which monitors the current and voltage levels provided by the LC circuit logging devices. If the current falls to zero on any individual phase, or if the three phase voltage relationship changes then this indicates that one or more of the fuses in the LV circuit being monitored have blown. As soon as the conditions have been met and detected by the master device, the master device activates its alarm bit. When the master device is polled by the radio (in the same manner as described above) the system determines that a fuse has blown on one of the LV circuits and provides an appropriate alarm.

The master device also monitors the 400V bus power quality. For example, the power quality value may be based on a measured RMS output voltage or peak output voltage, where the power quality is determined based on the measured power factor divided by the measured voltage value. An alarm may be activated if the monitored power quality value drops below a predetermined value or out of a predetermined range.

For example, the predetermined range may be between 0.9 and 1.1, or may be between 0.95 and 1.05. It will be understood that other ranges may be applied.

The smart distribution transformer also has LV circuit protection 113 to protect each of the LV circuits having power distributed to them from the transformer. It will be understood that each LV circuit is effectively a power circuit associated with a group of customers or an individual customer. Each of the LV circuit loggers 111 may therefore monitor the power circuits associated with one or more individual customers.

The LV circuit protection may effectively shut off or disconnect one or more LV circuits from the secondary side of the voltage transformer upon detection of one or more faults.

The LV circuit is protected by remotely operated circuit breakers so that one or more of the LV circuits may be disconnected from the 11 kV source. A fault monitoring module in the form of a Programmable Logic Controller (PLC) utilises phasor analysis to determine a fault condition. The PLC determines the positive, negative and zero sequence components resulting in a more precise fault calculation for each LV circuit.

For example, an electrical network can be modelled by positive, negative and zero sequence components. This method of calculation uses basic vector analysis to model each phase of the system. The mathematical representation allows analysis of the normal system model or to perform fault calculations quickly.

An explanation for each component of the fault calculations is provided as follows:

Zero sequence: This is the vectorial sum of measured three phase currents/voltages performed in real time. Ideally, this would be zero. However, in reality it never is. If there is an imbalance across the phases, it is determined by calculating this value. If this value is past a threshold, then it is determined that there is an earth fault or some serious imbalance in the network that requires attention. The equations for the Zero sequence components are as follows:

Positive and Negative sequence: These describe the direction of the three phase vector rotation. If there is an imbalance in these vector rotations it will represent phase to phase or open phase faults. Below are the equations for each type of component and the overall relationships for each phase voltage/current:

Positive Sequence Component:

Negative Sequence Component:

Phase current and voltage equations based on the sequence components:

According to an alternative embodiment, the LV circuit protection includes a fuse rack with standard fuses. For example, the fuse rack may be a Jean Muller fuse rack. Accordingly, the fault detection circuit only detects a LV circuit fault and is not able to automatically disconnect or reconnect LV circuits. A VAr compensation module 115 provides a system that enables power generated by an inductive power generator to be fed back to the power grid in an efficient manner. According to this embodiment, the VAr compensation module includes a power factor controller and a 3 stage 15kVAr unit that is controlled to automatically switch in capacitors based on a determined power factor. A staged capacitor bank incorporates three stages, each having a 5kVAr capacitor step. Each step may be switched in or out dependent on the power factor values monitored from the voltage transformer. It will be understood that alternative values and configurations may be utilised for the capacitor bank. Advantageously, the capacitor bank may be integrated into the smart distribution transformer to reduce system cost.

The power factor controller monitors and controls the power factor of the load by switching in the capacitor stages of the capacitor bank as needed.

For example, the power factor (PF) range may be set in the region of 0.95<PF<1.05, Therefore, if the load has a constant running reactive load of 4kVAr and the PF is 0.9, the controller is configured to switch in the first stage of 5kVAr capacitors. This means that the resultant PF will be either unity or just above based on the apparent load. If the running reactive load jumps to 6kVAr but the PF is 0.97, the controller is configured not to switch in any more stages. As such, as the PF increases, the capacitor bank stages are switched in to get the PF to above 0.95 and below 1.05. It will be understood that the power factor predetermined range may be varied accordingly.

It will be understood that the size of the unit and various components therein may be varied based on the transformer capacity/loading and distributed generation requirements.

The power factor monitoring system determines the power factor value by monitoring the single phase currents and voltages of the other two phases. Accordingly, by theorising a 3 phase balanced system and using phasor analysis of the current and voltage phasors, the system determines a power factor value that is used to switch the capacitors in to achieve the target power factor range.

In a system whereby power is generated from reactive power generators in order to feed power back into the grid, the ability to control and switch in various capacitive elements ensures that efficiency of the system is maintained. For example, the reactive power generators may be an inductive wind turbine. It will be understood that alternative reactive power generators may also be used with this system. Therefore, if the wind generator is connected direct to the power grid, it will lag the system frequency by a certain amount. As this lag increases, the higher the inductive impedance when viewed from the network connection point. To compensate for that, the smart distribution transformer’s capacitor banks inject reactive power required by the wind turbines. Without the capacitor banks, the voltage at the point of injection of power into the grid will vary along with variation in wind speed, ultimately resulting in voltage collapse and instability of the power system.

It will be understood that, as an alternative, the capacitor banks may also include one or more inductive elements. Therefore, the VAr compensation device may incorporate staged inductors as well as staged capacitors. The components of the compensation device can be used to fix leading or lagging power factor issues. Any suitable type of device may be used, such as SVC (static VAr compensator) and STATCOM (static synchronous compensator) devices, A second embodiment as shown in figure 2 will now be described. As in the first embodiment described above, the system includes an automated 11 kV switch with RTU and logging capabilities 103, a communications module 105, a transformer monitor 107 and an LV bus logger 109, and VAr compensation module 115. Each of these components has the same functionality as described above.

The voltage transformer 201 according to this embodiment includes the capability of allowing voltage regulation to occur. For example, a controllable inductor may be incorporated within the voltage transformer, The control unit of the smart transformer controls the voltage regulation based on selected inputs being monitored using various sensors. A load management module 203 provides the capability of shifting control from a central point such as a control room as in standard distribution transformers to a distributed point, i.e. the smart distribution transformer. The transformer communicates in real time via a mesh radio to individual communication units installed in smart meters, as explained below. The smart meter provides access to individual controllable load devices in the house. This means that the load on the smart distribution transformer can be switched and controlled in real time as and when required by the smart transformer itself.

Traditionally, voltage regulation in any three phase system needs to overcome problems such as voltage drops over long feeders or load imbalance. Hence, the traditional fix for this has been to manually adjust taps on normal transformers or shift loads. This practice works well for scenarios where voltages do not vary too much or tend to either go up or down, not both.

However, with the advent of distributed generation this standard practice of voltage regulation will not suffice. Distributed generation is based around renewable energies that are completely dependent on weather and so the voltages produced vary significantly during the day. It is impractical to send individuals out to manually change taps on normal transformers twice during the day. Therefore, if the voltages are not regulated properly, there can be severe voltage imbalances in between the different phases. Further, as the voltage levels on the three-phase this can vary considerably due to the generation of the renewable energy, many adjusting a transformer tap using traditional methods to compensate for a low voltage on the first phase may overcompensate for the other phases.

Automatic voltage regulation is therefore used at the transformer level. The smart transformer described herein has automatic voltage regulation.

The voltage regulation may be implemented utilising any suitable technology, such as, for example, utilising power electronic technology to switch existing taps, or setting up a LV voltage regulator on the secondary winding of the transformer.

According to one embodiment, a LV Voltage regulator is used in the smart transformer. It will be understood that other voltage regulation devices may be used.

The regulator regulates the voltages on all three phases independently of each other. For example, during the afternoon period, it may be adapted to maintain a low imbalance between the phases and during a sun down period, it may be adapted to tap up to maintain the regulatory voltages over all phases.

Therefore, the regulator provides regulation of the output voltage for different periods of the day by automatically adjusting voltage regulation on individual phases dependent on the time of the day. A fault analysis module 207 includes programmable protection elements that can be used to control thyristor breakers. The thyristor breakers may replace the fuses and establish automatic protection control for over current and earth faults for the LV circuits. Therefore, full automatic control over the switching of the thyristor breakers is provided in the case of a detected fault. LV circuit protection modules 211 are utilised to provide control over the switching of breakers in order to disconnect or reconnect LV circuits. These modules are utilised to replace standard fuses, which are single shot. Therefore, further load management capabilities are provided.

Power storage 209 may be provided to give customers emergency power under certain defined circumstances. For example, the transformer may be configured to understand whether a customer (or smart meter) requires emergency power. For example, this may be a requirement where people or customers are dependent on medical apparatus to sustain life. In this situation, when there is a source power failure, the transformer is configured to isolate the particular smart meter from the rest of the customers and supply power to that particular smart meter. In this way, the power from the storage devices only rooted to critical customers.

Further, it will be understood that battery technology may be utilised to provide emergency backup power. In this situation, the battery backup may provide storage not only in defined circumstances such as emergency situations, but for all customers. In this way, the backup power may act in a similar manner to an uninterrupted power supply (UPS) or an entire neighbourhood or group of customers.

Figure 3 shows a conceptual diagram of the smart transformer system communicating with various smart meters installed in customer's premises.

The smart transformer 301 receives 11 kV on the primary side 303 and outputs 440 V three-phase on the secondary side 305. A monitoring module 307 within the smart transformer 301 monitors various aspects of the power being received and output from the smart transformer as discussed above. A control module 309 communicates with control units using the mesh radio system as described above.

The monitoring module may be implemented using a programmable logic controller (PLC). The PLC generates a message that is transferred to the control module for further relay to the smart meters. The message generated is based on the required load management of the transformer and 11 kV network and is determined based on the measured values of the current or voltages being fed into or out of the transformer.

For example, the monitoring module may utilise current sensors in order to measure the currents on each phase flowing through the transformer. The PLC receives these values and analyses them to determine whether a problem exists and a message should be sent to one or more smart meters. The smart meter then disconnects or reconnects various controllable devices based on the received message. For example, the control units attached to the smart meter may be Zigbee communication modules.

The 440 V three-phase power lines are fed to individual smart meters 311 located at customer premises 310. It will be understood that the voltage is applied to the various premises may be either three-phase voltage or single phase voltage (e.g. 220 V or 240 V).

The smart meter 311 feeds the power via power lines 315 within the customer's premises to individual controllable devices 317. A controllable device is determined based upon an agreement between the owner of the premises and the powerline company. For example, the controllable device may be an air conditioning system, water heater, spa pool, large-scale refrigeration unit, electrical vehicle charging unit or similar devices whereby the temporary switching off of the device is non-disruptive to the customer. That is, for example, due to the operation of the device there may be a lag, such as a thermal lag, which results in negligible disruption to the customer.

The smart transformer, based on the monitored inputs being monitored by the monitoring module, is therefore able to control the load being applied to the transformer by switching in and out various controllable devices at the customer's premises.

The smart transformer communicates with each of the control units 313 by way of the control module 309 using the mesh radio system. This enables the smart transformer to communicate with a number of smart meters located in various customers' premises without requiring all of those premises to be within direct communication contact.

Therefore based on the operation of this system, loading on the transformer and the 11 kV distribution network may be maintained in an efficient manner. Effectively, demand is shifted using peak shaving techniques by either delaying the operation of certain controllable devices or by temporarily switching of other controllable devices depending on the load requirements. The effect of this control is to improve utilisation of the overall 11 kV network and where possible to reduce the effects of peak demand by managing the current flowing through the network.

Further, the system may be designed to send power generated by renewable resources, such as wind turbines, back to the grid at times of the day when demand is high.

Figure 4 shows an example of a circuit diagram for controlling the smart transformer. Three-phase 400 V bus bar connections 401 are monitored by a LV bus logger and transformer monitor in the form of a network analyser 403. The network analyser 403 uses current sensors 405 attached to each of the individual phases on the 400 V bus bars. Further, the network analyser monitors the voltage levels on the three-phase bus via switchable control lines 407. Also, the network analyser 403 monitors the temperature of the transformer using a temperature probe 409. .

The network analyser 403 is in communication with a power factor controller 411 via an RS485 communications bus. The power factor controller 411 monitors the current on at least one of the three-phase lines using a current sensor 413. Further, the power factor controller 411 monitors the voltage between at least two of the three-phase lines using connections 415 to the 400 V bus bar.

Based on the input received at the power factor controller 411 outputs may be provided to relay circuits 417 which are operated to switch in and out various stages of a capacitor bank 419, as explained above. Further, the power factor controller 411 may activate an alarm output 421 based on the determined power factor value. A number of sub modules 423 used to monitor the LV circuits 425 also communicate via the RS485 communications bus with the network analyser 403. Therefore, the network analyser 403 acts as a fault monitoring module which then communicates with various monitoring sub modules 423. Each of the monitoring sub modules 423 provides a unique identification associated with the individual low voltage circuits to the network analyser in order for the network analyser to determine where any potential problems detected occur.

In addition to power quality measurements, the system may also monitor current using current sensors on the LV circuits to determine if an over current situation exists. Further, residual current devices may be utilised to determine whether earthing problems exist. In each scenario, the monitoring modules detect a fault and provide an output in order to communicate to the network that a problem has occurred.

The network analyser 403 further includes an alarm output in communication with an alarm module 427. Therefore, if any of the sub modules 423 detect an issue with the LV circuits or the network analyser itself detects problems with the bus bar, an alarm output is produced.

The network analyser 403 is also in communication with an IP switch 429 over an Ethernet communications network 431. The IP switch is an Ethernet hub/switch that allows multiple Internet protocol devices to connect to each other.

The IP switch is also in communication via the Ethernet network to an mesh radio system 433 and a switchgear system 435 which enables the switching in and out of the 11 kV supply to the distribution transformer.

It will be understood that the DC circuits indicated on the circuit diagram are provided power by an internal battery.

Figures 5A to 5C show an example of a smart transformer unit according to an embodiment of the present invention.

Figure 5A shows the unit from the side, figure 5B shows the unit from the rear and figure 5C shows unit from the front.

The unit includes feeder CT terminals and 6A fused terminals 1, power factor CT connections 2, incomer CT terminals and 6A fused terminals 3, power factor isolator fuses 4, GPO (General Purpose Outlet) and RCD (Residual Current Device) 5, 24 V DC supply 6, oil level 24 V DC signal inverting relay 7, 230 VAC 6A supply isolator 8, mesh radio system 9, master device (network analyser) 10, LV circuit logging devices (sub modules) 11, power factor controller 12, capacitor bank (3x5 kVA steps), incomer 1000A vertical disconnector switch 14, power factor controller supply disconnector 15, generator connection cover 16, outgoer feeders 17, earth leads 18, switchgear frame 19, phase bus bars 20, insulated neutral bus bar 21, power factor CTs 22, neutral bar 23, incoming phase cables 24, neutral cable 25, cable tray 26, Ethernet adapter 27.

It will be understood that the positioning of the various elements as shown in figures 5A through to 5C may be varied.

According to a further alternative, an overhead version of the above described transformers may be implemented. This overhead transformer may include the same functionality as the above described embodiments. However, due to the physical limitations with installing the various components on overhead power poles, the individual components of the smart transformer may be distributed over the same pole or over multiple poles.

It will be understood that the embodiments of the present invention described herein are by way of example only, and that various changes and modifications may be made without departing from the scope of invention.

Claims

CLAIMS:

1. A smart distribution transformer system comprising a fault monitoring system for monitoring the operation of one or more low voltage circuits being provided power by the smart distribution transformer system, the fault monitoring system comprising a fault monitoring module adapted to: monitor the voltage and/or current associated with a low voltage circuit; determine the occurrence of a fault condition; and develop an output signal upon receiving an indication from the determination module that a fault condition has occurred.
2. The smart distribution transformer system of claim 1 wherein the monitoring system further comprises a radio module adapted to communicate with the monitoring system to determine the output from the fault monitoring module.
3. The smart distribution transformer system of claim 1 wherein the monitoring system further comprises a plurality of monitoring sub modules adapted to monitor the voltage and/or current associated with a plurality of individual low voltage circuits, wherein the fault monitoring module communicates with the monitoring sub modules to determine the status of each individual low voltage circuit.
4. The smart distribution transformer system of claim 3 wherein the monitoring sub modules are adapted to provide to the fault monitoring module a unique identification associated with the individual low voltage circuit.
5. The smart distribution transformer system of claim 1 wherein the fault monitoring module further comprises an alarm module which is adapted to output an alarm based on the output signal.
6. A smart distribution transformer system adapted to transform power received from a power grid into a three-phase power supply for a plurality of consumers, wherein the smart distribution transformer system is further adapted to feed power generated by an inductive power generator back to the power grid, the smart distribution transformer system comprising a power factor monitoring system for monitoring the power factor associated with three-phase power supply and a multistage capacitor bank circuit adapted to be applied to the three-phase power supply, wherein the monitoring system is further adapted to control the application of the multistage capacitor bank circuit dependent upon the monitored power factor.
7. The smart distribution transformer system of claim 6 wherein the inductive power generator is a wind turbine.
8. The smart distribution transformer system of claim 6 wherein the monitoring system monitors the voltage and current associated with the three-phase power supply to determine the power factor.
9. The smart distribution transformer system of claim 6 wherein the monitoring system is further adapted to connect or disconnect a stage of the multistage capacitor bank upon detection that the monitored power factor is not within predetermined limits.
10. The smart distribution transformer system of claim 9 wherein the monitoring system is further adapted to connect or disconnect further stages of the multistage capacitor bank upon detection that the monitored power factor is still not within predetermined limits.
11. The smart distribution transformer system of claim 9 wherein the monitoring system is further adapted to sequentially connect or disconnect single stages of the multistage capacitor bank upon detection that the power factor is not within predetermined limits.
12. The smart distribution transformer system of claim 9 wherein the predetermined limits are a power factor value of between 0.9 and 1.1.
13. The smart distribution transformer system of claim 12 wherein the predetermined limits are a power factor value of between 0.95 and 1.05.
14. The smart distribution transformer system of claim 9 wherein the multistage capacitor bank circuit includes a three stage capacitor bank.
15. The smart distribution transformer system of claim 14 wherein each of the stages of the three stage capacitor bank are 5kVAr capacitors.
16. A smart distribution transformer comprising a control system for controlling the load applied to the smart distribution transformer, the control system comprising: a monitoring module adapted to monitor the operation of the smart distribution transformer and develop an output based on the monitored operation; and a control module adapted to wirelessly communicate with at least one smart meter where the smart meter is arranged to wirelessly communicate with at least one controllable device; wherein the control module is further adapted to transmit a control signal to the smart meter to instruct the smart meter to connect or disconnect the controllable device based on the output of the monitoring module.
17. The smart distribution transformer of claim 16 further comprising at least one sensor adapted to monitor one or more of the currents flowing through the transformer, efficiency of the transformer, voltage levels on the input or output power lines of the transformer and power factor values associated with the transformer, and the monitoring module is further adapted to monitor the output of the sensor.
18. The smart distribution transformer of claim 16 wherein the control module is further adapted to modify the peak loading of the smart distribution transformer based on the output of the monitoring module. „
19. The smart distribution transformer of claim 16 wherein the control module is further adapted to maintain the loading on the transformer within predetermined parameters.
20. The smart distribution transformer of claim 16 wherein the control module includes a wireless communication device that is adapted to communicate with the smart meter by way of a mesh radio system.
21. The smart distribution transformer of claim 20 wherein the wireless communication device is adapted to communicate with the smart meter via at least one further wireless communication device.
22. The smart distribution transformer of claim 20 wherein the wireless communication device is adapted to operate on one of a plurality of communication channels.
23. The smart distribution transformer of claim 16 wherein the control module comprises a programmable logic controller.
24. The smart distribution transformer of claim 16 wherein the monitoring module is further adapted to monitor the voltage being supplied by the transformer in order to determine a power quality value associated with properties being supplied power by the transformer.
25. The smart distribution transformer of claim 24 whereupon determination that the power quality value has varied beyond a predetermined value, the monitoring module is further adapted to develop an output voltage modification signal to adapt the output voltage of the transformer.
26. The smart distribution transformer of claim 25 wherein the power quality value is based on one of the RMS output voltage, peak output voltage.
27. The smart distribution transformer system of claim 1 including an automatic voltage regulator.
28. The smart distribution transformer system of claim 6 including an automatic voltage regulator.
29. The smart distribution transformer system of claim 6 including a transformer incorporating the multistage capacitor bank circuit.
30. The smart distribution transformer of claim 15 including an automatic voltage regulator.
31. A smart distribution transformer substantially as herein described with reference to the accompanying drawings.